Application of Air Foam DTH Hammer Drilling Technology during the Emergency Refuge Hole Drilling in Wangjialing Coal Mine

Abstract:

Air foam DTH hammer drilling technology was used in the emergency refuge hole drilling in Wangjialing coal mine, by which the high verticality requirement of the borehole was met and formation leakage was effectively controlled to realize quick drilling. The achieved average penetration rate was as high as 7.99 m/h and the final hole horizontal displacement was only 0.48m with the second stage comprehensive cost 504.8RMB per meter. The mud was used as circulation medium with cone rotary positive circulation drilling technology in the adjacent SW1 additional hydrological exploration hole, the average ROP was 0.86 m/h with the second stage comprehensive cost 820.5RMB per meter. The average mechanical drilling rate of the former is about 9 times of the latter and is more economical than the latter by 38.5%. Compared with the cone rotary positive circulation drilling used in the adjacent well, by the use of air foam DTH hammer drilling technology, the difficulties in the emergency refuge hole drilling were solved with higher borehole quality, shorter construction period and lower cost to increase efficiency by reducing cost.

Key words:air foam DTH hammer drilling; emergency refuge hole; drilling technology; Wangjialing coal mine